This invention relates to the monitoring of local area networks and, more particularly, in a cable connecting system connecting a first device to a second device with a cable carrying binary information between the first device and the second device over a wire contained in the cable, to the improvement for monitoring activity on the wire comprising, series connection means for inserting a connecting wire in series with the wire in the cable; signal sampling and triggering means connected to the connecting wire for sensing any binary signals on the connecting wire and for producing a trigger output when a binary signal is sensed; an illuminatable visible indicator; and, monostable device means having the trigger output connected to an input thereof and an output connected to the indicator for producing a signal at the output of sufficient duration to illuminate the indicator for a visibly detectable period of time.
The use of local area networks (LANs) to interconnect a number of computing entities has become common place in even small installations. Small businesses, law firms, and the like, routinely interconnect personal computers (PCs) throughout the office and use them to pass information back and forth and to share common printers, modems, etc. over the LAN.
In large, multi-processor installations such as constructed by governmental agencies and large corporations, integral diagnostic routines are commonly employed as the computers typically operate in co-operation with one another to perform a common task or mission on a resources allocation or distributed processing basis. In such an environment, the condition of the LAN and its ability to reliably transmit messages between the computers of the system is of critical importance. If the LAN is totally inoperative (a rare case), this must be sensed as quickly as possible so the maintenance personnel can find and repair the problem. The more usual "failure" condition is a problem at one or more of the interfaces of the computers with the LAN (requiring rerouting of the messages) or excessive traffic on the LAN in whole or in part which causes increased overhead due to the retransmitting of lost or destroyed messages.
While some of these aspects are applicable to a LAN of the token passing variety, they are most prevalent in a contention type of LAN environment. For small business installations, and the like, in particular, a contention LAN is the easiest and least costly to install. The most common is that sold under the name Ethernet which is the trademark for the Carrier Sensing Multiple Access/Collision Detection local area networking protocol developed by Digital Equipment Corporation (DEC), Xerox, and Hewlett-Packard, and IEEE 802.3 Standard (available to the public) applications market. While the status of the LAN as far as traffic, etc. is of interest to the smaller user as well as the larger user who can afford to pay the high cost of an integrated LAN monitoring, diagnostic, and correction system, there is nothing in the prior art which will visually advise the small user about the status of his LAN on a simple and low-cost basis.
Wherefore, it is an object of this invention to provide a very small device which can be inserted in series with the connection of a computer to a LAN which will visually advise the user about the status of his LAN on a simple and low-cost basis.
It is another object of this invention to provide a device which can be inserted in series with the connection of a computer to a LAN at opposite ends of a LAN cable which will visually advise the small user about the health of the cable on a simple and low-cost basis.
Other objects and benefits of the invention will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.